1. Field of the Invention
The present invention relates to apparatus for the subjective examination of eye refractive power.
2. Description of the Prior Art
In order to examine eye refractive power there has conventionally been used such apparatus which comprises two boxes containing therein a number of lenses having different refractive powers. The two boxes which are to be placed in front of the right and left eyes to be examined, have each a window through which the examinee looks at a mark through one of the lenses contained in the boxes. With this apparatus, the eye examination is conducted in the following manner:
The examiner sets the apparatus immediately before the eyes to be examined and lets the examinee look at a mark through a lens selected from the lenses contained in the boxes. The mark is at a position, for example, 5 meters distant from the apparatus. The examiner changes the lens from one to another while asking the examinee whether he can view the mark well or not until the examiner finds out the lens through which the examinee can view the mark best. The examiner determines the refractive power of the examined eye from the refractive power of the lens.
The conventional eye examining apparatus has some important drawbacks. Since the apparatus contains many lenses therein, it is very complicated in construction and expensive. In addition, it needs a relatively wide room for conducting the examination because the mark has to be set at a distant point from the apparatus. Thus, the place available for the eye examination has been limited.